The unpardonable sin
There is one sin that will forever close the door to the Kingdom of God - the expression of discontent and condemnation of his actions. An Orthodox Christian should always remember about it and not to make a fatal error. This sin is called pride and is considered to be an original. According to the Bible, Lucifer was banished from heaven to earth because of the fact that I dared to Express dissatisfaction with the existing order.
Other sins
There are 7 deadly sins. Pride is one of them. They are called mortal because they kill the life of the soul. If a person commits serious misconduct too often, he may forever alienate himself from God and his true ways. In this case, he can only rely on God's mercy and forgiveness.
Greed is today's most common sin. People are so absorbed by their material wealth (or lack thereof), he forgets about his soul, that he is imperfect and he must rely on the help and grace of God. Greed exacerbate the "dirty" money that people earned in a dishonest way.
Fornication is another common sin. Sometimes the animal rights takes precedence over his spiritual longings, and the man indulges in all serious. In Orthodoxy, even depraved look at a woman is considered fornication. Swearing, reading and watching pornographic materials is also considered sinful.
Envy is sinful only if it leads to harming one's neighbor. This so-called "black" envy. It resembles that of pride, as a man, jealous of someone, also expressed dissatisfaction with the existing order of things established by God.
Discouragement leads to depression and sometimes to suicide. It all starts with the fact that the person is simply too lazy to do good deeds and to arrange his life. It is gradually moving in that man ceases to fear God and rely on him.
Anger clouds the mind of a person and possesses them. For him man is capable of anything just to get rid of this unpleasant feelings. Often motivated by anger are strife and murder. Of course, it does not always end in physical abuse, but the hatred and enmity between people necessarily remains.
Gluttony is reflected in the use of drugs and alcohol, as well as compliance with prescribed posts.